A thermoplastic bag for the storage of items typically includes a closure mechanism comprising male and female closure elements or profiles attached to an inner surface of a bag wall. In addition, thermoplastic bags are known having one or more pairs of ribs on outer surface(s) of the bag wall straddling at least one of the closure elements to guide a user's fingers when sealing the closure elements. Ribs have also been used on an internal surface of the thermoplastic bag closely spaced and adjacent the closure elements to assist in aligning the male and female closure elements when sealing the bag.
Hugues et al., U.S. Pat. No. 4,672,723 discloses a stabilized reclosable extruded plastic fastener. The fastener comprises a female profile on one wall of an extruded film material and a male profile on an opposite wall of the film material. Alignment ribs are spaced alongside and integral with a base area of the male profile to facilitate alignment of the male profile with the female profile during closing of the fastener.
Fisher U.S. Pat. No. 4,736,496, owned by the assignee of the present application, discloses a wide-track integral thermoplastic closure for a reclosable thermoplastic container. The closure includes ribs on either side of an element of the closure to assist in guiding a user's fingers during closure of the thermoplastic container.
Tilman et al., U.S. Pat. No. 4,929,487 discloses a thermoplastic bag having male and female fastener profiles and at least one alignment rib integral with the film and disposed on an outer surface of a bag wall opposite and aligned with the male profile. The rib functions to stiffen the area of film occupied by the male profile and facilitate the alignment of the male and female fastener profiles.
Porchia et al., U.S. Pat. No. 5,012,561, also owned by the assignee of the present application discloses a closure for reclosable thermoplastic containers. The closure comprises male and female closure elements, wherein the male closure element includes a male profile member and ribs disposed on either side of the male profile member and attached thereto by a base. The ribs are of a sufficient size and proximity to the male profile member so as to move together as a unit with the male profile member when the male and female closure elements are engaged or disengaged.
Dais et al., U.S. Pat. No. 5,140,727, owned by the assignee of the present application, discloses a zipper for reclosable thermoplastic bags and a process and apparatus for making the same. The zipper comprises opposing longitudinally extending interlockable rib and groove profiles. The rib profile defines a bulbous head that is generally triangularly shaped in cross-section, a stem, and optionally, one or more ribs adjacent the stem.
Tilman, U.S. Pat. No. 5,209,574 discloses a reclosable plastic bag having a sliderless zipper. The bag includes front and rear walls sealed along three edges to form a mouth or opening. Male and female profiles are attached to internal surfaces of the front and rear walls, respectively, wherein the male and female profiles are engageable to close the opening. Two ribs are provided on an outside surface of the front wall, one on each side of the male profile, to define a valley therebetween. Similarly, two additional ribs are formed on the outside surface of the rear wall, one on each side of female profile, to define a valley therebetween. The valleys act as finger guides for the user of the bag.
Scott et al., U.S. Pat. No. 5,368,394 discloses a reclosable bag having a stabilizer wedge zipper. The reclosable bag comprises front and rear walls sealed along three edges to form an opening. Male and female profiles are attached to internal faces of the walls. Each of the male and female profiles includes two stabilizer wedges that assist in transmitting forces to male and female profiles during opening of the bag.
Thermoplastic bags have also been developed having spaced multiple closure mechanisms. For example, a bag manufactured by Thai Griptech Company, Ltd. of Bangkok, Thailand, includes a first and second spaced closure mechanisms disposed at a top portion of the bag. Each closure mechanism includes a male closure portion and a female closure portion, wherein the male closure portions are disposed on a first bag wall and the female closure portions are disposed on a second bag wall opposite the male closure portions. The first closure mechanism is disposed approximately ⅜ths inch from the second closure mechanism. Apparently, the closure mechanisms have substantially identical closure characteristics in the sense of the force required to occlude the closure portions of each closure mechanism, the feel experienced by the user when occluding or de-occluding the closure portions of each closure mechanism, the resistances to de-occlusion to forces acting on either side of the closure mechanism, etc . . . Also, the intention is to fully close the bag by undertaking two zipping operation to separately close the closure mechanisms.